Daiki Asuka is a fourteen-year-old boy at St. Paulia's Private School, and is a top student in his class. His physical strength and motor skills are lacking. Called Asuka Jr. by his classmates, Daiki Asuka is the son of Detective Tomoki Asuka. Because his father has been unable to catch Saint Tail, and doesn't place any emergency on this thief's capture, Asuka Jr. takes to task. He plans to one-up his father by catching Saint Tail.